Zoom lens system, interchangeable lens apparatus and camera system

ABSTRACT

A zoom lens system comprising a plurality of movable lens units which individually move along an optical axis at the time of zooming from a wide-angle limit to a telephoto limit during image taking, wherein at least two of the movable lens units are focusing lens units which move along the optical axis at the time of focusing from an infinity in-focus condition to a close-object in-focus condition in at least one zooming position, and among the focusing lens units, a lens unit having the absolute value, which is not the greatest absolute value, of a wobbling value at a wide-angle limit is a wobbling lens unit which senses a moving direction of the focusing lens units at the time of focusing by wobbling itself in a direction along the optical axis; an interchangeable lens apparatus; and a camera system are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on application No. 2010-065052 filed in Japanon Mar. 19, 2010, the contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system, an interchangeablelens apparatus, and a camera system. In particular, the presentinvention relates to: a compact and lightweight zoom lens system havinga relatively high zooming ratio, in which aberration fluctuation inassociation with focusing is reduced, aberrations particularly in aclose-object in-focus condition are sufficiently compensated to provideexcellent optical performance over the overall focusing condition, andcontinuous high-speed autofocusing performance extremely being suitablefor image taking of videos is provided; and an interchangeable lensapparatus and a camera system each employing this zoom lens system.

2. Description of the Background Art

In recent years, interchangeable-lens type digital camera systems (alsoreferred to simply as “camera systems”, hereinafter) have been spreadingrapidly. Such interchangeable-lens type digital camera systems canrealize: taking of a high-sensitive and high-quality image; high-speedfocusing and high-speed image processing after image taking; and easyreplacement of an interchangeable lens apparatus in accordance with adesired scene. Furthermore, an interchangeable lens apparatus having azoom lens system that forms an optical image with variable magnificationis popular because it allows free change of focal length without thenecessity of lens replacement.

A compact zoom lens system having a high zooming ratio and excellentoptical performance from a wide-angle limit to a telephoto limit hasbeen desired as a zoom lens system to be used in an interchangeable lensapparatus. Various kinds of zoom lens systems having multiple-unitconfigurations, such as four-unit configuration and five-unitconfiguration, have been proposed. In such zoom lens systems, focusingis usually performed such that some lens units in the lens system aremoved in a direction along the optical axis. However, when focusing froman infinity in-focus condition to a close-object in-focus condition isperformed by a single lens unit, the amount of movement at focusing ofthis lens unit depends on paraxial power configuration in the entirelens system. Therefore, it is difficult to favorably compensate theamount of aberration fluctuation from a wide angle limit to a telephotolimit.

In order to reduce aberration fluctuation at the time of focusing,various zoom lens systems are proposed, in which a plurality of lensunits in the lens system are individually moved in the direction alongthe optical axis.

Japanese Patent No. 4402368 discloses a zoom lens having four-unitconfiguration of positive, negative, negative, and positive. In thiszoom lens, at the time of zooming, a first lens unit and a fourth lensunit move from the image side to the object side, and thereby theintervals between the respective lens units are changed. At the time offocusing, a second lens unit moves to the image side at a wide-anglelimit and moves to the object side at a telephoto limit, and a thirdlens unit moves to the object side regardless of the zooming condition.The amounts of movement at the time of focusing of the second and thirdlens units are set forth.

Japanese Laid-Open Patent Publication No. 2009-169051 discloses a zoomlens having three-or-more-unit configuration, in which a negative lensunit is located closest to the object side. In this zoom lens, theintervals between the respective lens units are changed at the time ofzooming. A first focusing unit and a second focusing unit which includesa positive lens and a negative lens individually move at the timing offocusing. Abbe numbers of the positive lens and the negative lens areset forth.

Japanese Laid-Open Patent Publication No. 11-072705 discloses a zoomlens having a six-unit configuration of positive, negative, positive,positive, negative, and positive. In this zoom lens, at the time ofzooming, at least one magnification-variable lens unit among the secondto sixth lens units moves along the optical axis. At least one of thethird to sixth lens units is moved along the optical axis to compensatevariation in the image point position due to the zooming. At least twofocusing lens units among the first to sixth lens units are moved alongthe optical axis to perform focusing.

In each of the zoom lenses disclosed in the above-described patentliteratures, the aberration fluctuation at the time of focusing isreduced to some extent. However, since compensation of aberrations,particularly in a close-object in-focus condition, is insufficient, thezoom lenses do not have excellent optical performance over the entireobject distance from an infinite object distance to a close objectdistance.

In recent years, among the camera systems, particularly a video camerasystem for image taking of videos is strongly desired, and a zoom lenssystem which is able to continuous high-speed autofocus is needed.However, the zoom lenses disclosed in the above-described patentliteratures do not have continuous high-speed autofocusing performancebeing applicable for such the video camera system.

SUMMARY OF THE INVENTION

An object of the present invention is to provide: a compact andlightweight zoom lens system having a relatively high zooming ratio, inwhich aberration fluctuation in association with focusing is reduced,aberrations particularly in a close-object in-focus condition aresufficiently compensated to provide excellent optical performance overthe overall focusing condition, and continuous high-speed autofocusingperformance extremely being suitable for image taking of videos isprovided; and an interchangeable lens apparatus and a camera system eachemploying this zoom lens system.

The novel concepts disclosed herein were achieved in order to solve theforegoing problems in the conventional art, and herein is disclosed:

a zoom lens system comprising a plurality of lens units, each lens unitcomprising at least one lens element, wherein

the plurality of lens units include a plurality of movable lens unitswhich individually move along an optical axis at the time of zoomingfrom a wide-angle limit to a telephoto limit during image taking,

at least two of the movable lens units are focusing lens units whichmove along the optical axis at the time of focusing from an infinityin-focus condition to a close-object in-focus condition in at least onezooming position from a wide-angle limit to a telephoto limit, and

among the focusing lens units, a lens unit having the absolute value,which is not the greatest absolute value, of a wobbling value at awide-angle limit represented by the following expression (a) is awobbling lens unit which senses a moving direction of the focusing lensunits at the time of focusing by wobbling itself in a direction alongthe optical axis:

W=1/e+β _(WO)/(Sb×f _(WO))−1/((β_(R) ×f _(R))  (a)

where

W is a wobbling value at a wide-angle limit (wobbling incrementalmagnification sensitivity),

Sb is a focus sensitivity of the wobbling lens unit represented by thefollowing expression

Sb=(1−β_(WO) ²)×β_(R) ²,

e is an exit pupil position of the entire system at a wide-angle limit,

β_(WO) is a paraxial lateral magnification of the wobbling lens unit ata wide-angle limit in an infinity in-focus condition,

f_(WO) is a focal length of the wobbling lens unit at a wide-angle limitin an infinity in-focus condition,

β_(R) is a paraxial lateral magnification of a system on the image siderelative to the wobbling lens unit at a wide-angle limit in an infinityin-focus condition, and

f_(R) is a focal length of a system on the image side relative to thewobbling lens unit at a wide-angle limit in an infinity in-focuscondition.

The novel concepts disclosed herein were achieved in order to solve theforegoing problems in the conventional art, and herein is disclosed:

an interchangeable lens apparatus comprising:

a zoom lens system; and

a lens mount section which is connectable to a camera body including animage sensor for receiving an optical image formed by the zoom lenssystem and converting the optical image into an electric image signal;wherein

the zoom lens system comprises a plurality of lens units, each lens unitcomprising at least one lens element, in which

the plurality of lens units include a plurality of movable lens unitswhich individually move along an optical axis at the time of zoomingfrom a wide-angle limit to a telephoto limit during image taking,

at least two of the movable lens units are focusing lens units whichmove along the optical axis at the time of focusing from an infinityin-focus condition to a close-object in-focus condition in at least onezooming position from a wide-angle limit to a telephoto limit, and

among the focusing lens units, a lens unit having the absolute value,which is not the greatest absolute value, of a wobbling value at awide-angle limit represented by the following expression (a) is awobbling lens unit which senses a moving direction of the focusing lensunits at the time of focusing by wobbling itself in a direction alongthe optical axis:

W=1/e+β _(WO)/(Sb×f _(WO))−1/(β_(R) ×f _(R))  (a)

where

W is a wobbling value at a wide-angle limit (wobbling incrementalmagnification sensitivity),

Sb is a focus sensitivity of the wobbling lens unit represented by thefollowing expression

Sb=(1−β_(WO) ²)×β_(R) ²,

e is an exit pupil position of the entire system at a wide-angle limit,

β_(WO) is a paraxial lateral magnification of the wobbling lens unit ata wide-angle limit in an infinity in-focus condition,

f_(WO) is a focal length of the wobbling lens unit at a wide-angle limitin an infinity in-focus condition,

β_(R) is a paraxial lateral magnification of a system on the image siderelative to the wobbling lens unit at a wide-angle limit in an infinityin-focus condition, and

f_(R) is a focal length of a system on the image side relative to thewobbling lens unit at a wide-angle limit in an infinity in-focuscondition.

The novel concepts disclosed herein were achieved in order to solve thefo regoing problems in the conventional art, and herein is disclosed:

a camera system comprising:

an interchangeable lens apparatus including a zoom lens system; and

a camera body which is detachably connected to the interchangeable lensapparatus via a camera mount section, and includes an image sensor forreceiving an optical image formed by the zoom lens system and convertingthe optical image into an electric image signal; wherein

the zoom lens system comprises a plurality of lens units, each lens unitcomprising at least one lens element, in which

the plurality of lens units include a plurality of movable lens unitswhich individually move along an optical axis at the time of zoomingfrom a wide-angle limit to a telephoto limit during image taking,

at least two of the movable lens units are focusing lens units whichmove along the optical axis at the time of focusing from an infinityin-focus condition to a close-object in-focus condition in at least onezooming position from a wide-angle limit to a telephoto limit, and

among the focusing lens units, a lens unit having the absolute value,which is not the greatest absolute value, of a wobbling value at awide-angle limit represented by the following expression (a) is awobbling lens unit which senses a moving direction of the focusing lensunits at the time of focusing by wobbling itself in a direction alongthe optical axis:

W=1/e+β _(WO)/(Sb×f _(WO))−1/((β_(R) ×f _(R))  (a)

where

W is a wobbling value at a wide-angle limit (wobbling incrementalmagnification sensitivity),

Sb is a focus sensitivity of the wobbling lens unit represented by thefollowing expression

Sb=(1−β_(WO) ²)×β_(R) ²,

e is an exit pupil position of the entire system at a wide-angle limit,

β_(WO) is a paraxial lateral magnification of the wobbling lens unit ata wide-angle limit in an infinity in-focus condition,

f_(WO) is a focal length of the wobbling lens unit at a wide-angle limitin an infinity in-focus condition,

β_(R) is a paraxial lateral magnification of a system on the image siderelative to the wobbling lens unit at a wide-angle limit in an infinityin-focus condition, and

f_(R) is a focal length of a system on the image side relative to thewobbling lens unit at a wide-angle limit in an infinity in-focuscondition.

According to the present invention, it is possible to provide: a compactand lightweight zoom lens system having a relatively high zooming ratio,in which aberration fluctuation in association with focusing is reduced,aberrations particularly in a close-object in-focus condition aresufficiently compensated to provide excellent optical performance overthe overall focusing condition, and variation in image takingmagnification due to wobbling is suppressed in spite of continuoushigh-speed autofocusing performance extremely being suitable for imagetaking of videos; and an interchangeable lens apparatus and a camerasystem each employing this zoom lens system.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other objects and features of this invention will become clearfrom the following description, taken in conjunction with the preferredembodiments with reference to the accompanied drawings in which:

FIG. 1 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 1 (Example 1);

FIG. 2 is a longitudinal aberration diagram of an infinity in-focuscondition of a zoom lens system according to Example 1;

FIG. 3 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 1;

FIG. 4 is a lateral aberration diagram of a zoom lens system accordingto Example 1 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;

FIG. 5 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 2 (Example 2);

FIG. 6 is a longitudinal aberration diagram showing an infinity in-focuscondition of a zoom lens system according to Example 2;

FIG. 7 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 2;

FIG. 8 is a lateral aberration diagram of a zoom lens system accordingto Example 2 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;

FIG. 9 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 3 (Example 3);

FIG. 10 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 3;

FIG. 11 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 3;

FIG. 12 is a lateral aberration diagram of a zoom lens system accordingto Example 3 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;

FIG. 13 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 4 (Example 4);

FIG. 14 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 4;

FIG. 15 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 4;

FIG. 16 is a lateral aberration diagram of a zoom lens system accordingto Example 4 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;

FIG. 17 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 5 (Example 5);

FIG. 18 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 5;

FIG. 19 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 5;

FIG. 20 is a lateral aberration diagram of a zoom lens system accordingto Example 5 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;

FIG. 21 is a lens arrangement diagram showing an infinity in-focuscondition of a zoom lens system according to Embodiment 6 (Example 6);

FIG. 22 is a longitudinal aberration diagram showing an infinityin-focus condition of a zoom lens system according to Example 6;

FIG. 23 is a longitudinal aberration diagram of a close-object in-focuscondition of a zoom lens system according to Example 6;

FIG. 24 is a lateral aberration diagram of a zoom lens system accordingto Example 6 at a telephoto limit in a basic state where image blurcompensation is not performed and in an image blur compensation state;and

FIG. 25 is a schematic construction diagram of an interchangeable-lenstype digital camera system according to Embodiment 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 to 6

FIGS. 1, 5, 9, 13, 17, and 21 are lens arrangement diagrams of zoom lenssystems according to Embodiments 1 to 6, respectively. Each Fig. shows azoom lens system in an infinity in-focus condition.

In each Fig., part (a) shows a lens configuration at a wide-angle limit(in the minimum focal length condition: focal length f_(W)), part (b)shows a lens configuration at a middle position (in an intermediatefocal length condition: focal length f_(M)=√(f_(W)*f_(T))), and part (c)shows a lens configuration at a telephoto limit (in the maximum focallength condition: focal length f_(T)). Further, in each Fig., each bentarrow located between part (a) and part (b) indicates a line obtained byconnecting the positions of each lens unit respectively at a wide-anglelimit, a middle position and a telephoto limit, in order from the top.In the part between the wide-angle limit and the middle position, andthe part between the middle position and the telephoto limit, thepositions are connected simply with a straight line, and hence this linedoes not indicate actual motion of each lens unit.

Moreover, in each Fig., an arrow imparted to a lens unit indicatesfocusing from an infinity in-focus condition to a close-object in-focuscondition. That is, in FIGS. 1 and 5, the arrow indicates the movingdirection of a second lens unit G2 and a fourth lens unit G4, which aredescribed later, at the time of focusing from an infinity in-focuscondition to a close-object in-focus condition. In FIGS. 9 and 13, thearrow indicates the moving direction of the second lens unit G2 and afifth lens unit G5, which are described later, at the time of focusingfrom an infinity in-focus condition to a close-object in-focuscondition. In FIGS. 17 and 21, the arrow indicates the moving directionof the second lens unit G2, a third lens unit G3, and the fifth lensunit G5, which are described later, at the time of focusing from aninfinity in-focus condition to a close-object in-focus condition. InFIGS. 1, 5, 9, 13, 17, and 21, since the symbols of the respective lensunits are imparted to part (a), the arrow indicating focusing is placedbeneath each symbol of each lens unit for the convenience sake. However,the direction along which each lens unit moves at the time of focusingin each zooming condition will be hereinafter described in detail foreach embodiment.

Each of the zoom lens systems according to Embodiments 1 and 2, in orderfrom the object side to the image side, comprises a first lens unit G1having positive optical power, a second lens unit G2 having negativeoptical power, a third lens unit G3 having positive optical power, afourth lens unit G4 having negative optical power, and a fifth lens unitG5 having positive optical power. In the zoom lens systems according toEmbodiments 1 and 2, at the time of zooming, the second lens unit G2 andthe fourth lens unit G4 individually move in the direction along theoptical axis so that the intervals between the respective lens units,i.e., the interval between the first lens unit G1 and the second lensunit G2, the interval between the second lens unit G2 and the third lensunit G3, the interval between the third lens unit G3 and the fourth lensunit G4, and the interval between the fourth lens unit G4 and the fifthlens unit G5, vary. In the zoom lens systems according to Embodiments 1and 2, these lens units are arranged in a desired optical powerconfiguration, and thereby size reduction is achieved in the entire lenssystem while maintaining high optical performance.

Each of the zoom lens systems according to Embodiments 3 to 6, in orderfrom the object side to the image side, comprises a first lens unit G1having positive optical power, a second lens unit G2 having negativeoptical power, a third lens unit G3, a fourth lens unit G4 havingpositive optical power, a fifth lens unit G5 having negative opticalpower, and a sixth lens unit G6 having positive optical power. In thezoom lens systems according to Embodiments 3 and 4, the third lens unitG3 has positive optical power. In the zoom lens systems according toEmbodiments 5 and 6, the third lens unit G3 has negative optical power.In the zoom lens systems according to Embodiments 3 to 6, at the time ofzooming, the second lens unit G2, the third lens unit G3, and the fifthlens unit G5 individually move in the direction along the optical axisso that the intervals between the respective lens units, i.e., theinterval between the first lens unit G1 and the second lens unit G2, theinterval between the second lens unit G2 and the third lens unit G3, theinterval between the third lens unit G3 and the fourth lens unit G4, theinterval between the fourth lens unit G4 and the fifth lens unit G5, andthe interval between the fifth lens unit G5 and the sixth lens unit G6,vary. In the zoom lens systems according to Embodiments 3 to 6, theselens units are arranged in a desired optical power configuration, andthereby size reduction is achieved in the entire lens system whilemaintaining high optical performance.

Further, in FIGS. 1, 5, 9, 13, 17, and 21, an asterisk “*” imparted to aparticular surface indicates that the surface is aspheric. In each Fig.,symbol (+) or (−) imparted to the symbol of each lens unit correspondsto the sign of the optical power of the lens unit. In each Fig., thestraight line located on the most right-hand side indicates the positionof the image surface S.

Further, as shown in FIGS. 1 and 5, an aperture diaphragm A is providedbetween a ninth lens element L9 and a tenth lens element L10 in thethird lens unit G3. As shown in FIGS. 9 and 13, an aperture diaphragm Ais provided on the most object side in the fourth lens unit G4, i.e., onthe object side relative to an eleventh lens element L11. As shown inFIGS. 17 and 21, an aperture diaphragm A is provided between a seventhlens element L7 and an eighth lens element L8 in the fourth lens unitG4.

As shown in FIG. 1, in the zoom lens system according to Embodiment 1,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a positive meniscus second lens elementL2 with the convex surface facing the object side, and a bi-convex thirdlens element L3. The first lens element L1, the second lens element L2,and the third lens element L3 are cemented with each other. The thirdlens element L3 is an aspherical lens element formed of a thin layer ofresin or the like, and has an aspheric image side surface.

In the zoom lens system according to Embodiment 1, the second lens unitG2, in order from the object side to the image side, comprises abi-concave fourth lens element L4, a bi-concave fifth lens element L5,and a positive meniscus sixth lens element L6 with the convex surfacefacing the object side. Among these, the fifth lens element L5 has anaspheric object side surface. The second lens unit G2 is a lens unithaving the greatest absolute value of optical power among all the lensunits, as shown in Numerical Example 1 described later. Also, the secondlens unit G2 is a lens unit having the greatest absolute value of awobbling value at a wide-angle limit among the focusing lens units, asshown in Numerical Example 1 described later.

In the zoom lens system according to Embodiment 1, the third lens unitG3, in order from the object side to the image side, comprises apositive meniscus seventh lens element L7 with the convex surface facingthe object side, a negative meniscus eighth lens element L8 with theconvex surface facing the object side, a positive meniscus ninth lenselement L9 with the convex surface facing the object side, a bi-convextenth lens element L10, and a negative meniscus eleventh lens elementL11 with the convex surface facing the image side. Among these, theeighth lens element L8 and the ninth lens element L9 are cemented witheach other, and the tenth lens element L10 and the eleventh lens elementL11 are cemented with each other. The ninth lens element L9 has anaspheric image side surface, and the tenth lens element L10 has anaspheric object side surface. Further, an aperture diaphragm A isprovided between the ninth lens element L9 and the tenth lens elementL10.

In the zoom lens system according to Embodiment 1, the fourth lens unitG4, in order from the object side to the image side, comprises anegative meniscus twelfth lens element L12 with the convex surfacefacing the object side, and a bi-concave thirteenth lens element L13.

In the zoom lens system according to Embodiment 1, the fifth lens unitG5 comprises solely a bi-convex fourteenth lens element L14. Thefourteenth lens element L14 has an aspheric image side surface.

In the zoom lens system according to Embodiment 1, the fourth lens unitG4 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 1, the tenth lenselement L10 and the eleventh lens element L11 in the third lens unit G3correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 1, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 and the fourth lens unit G4monotonically move to the image side, and the first lens unit G1, thethird lens unit G3, and the fifth lens unit G5 are fixed relative to theimage surface S. That is, in zooming, the second lens unit G2 and thefourth lens unit G4 individually move along the optical axis so that theinterval between the first lens unit G1 and the second lens unit G2 andthe interval between the third lens unit G3 and the fourth lens unit G4increase, and the interval between the second lens unit G2 and the thirdlens unit G3 and the interval between the fourth lens unit G4 and thefifth lens unit G5 decrease.

Further, in the zoom lens system according to Embodiment 1, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 does not move along theoptical axis at a wide-angle limit, but moves to the object side alongthe optical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the fourth lens unit G4 moves to the image sidealong the optical axis at a wide-angle limit, and moves to the objectside along the optical axis in other zooming conditions.

As shown in FIG. 5, in the zoom lens system according to Embodiment 2,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a bi-convex second lens element L2, anda positive meniscus third lens element L3 with the convex surface facingthe image side. The first lens element L1, the second lens element L2,and the third lens element L3 are cemented with each other. The thirdlens element L3 is an aspherical lens element formed of a thin layer ofresin or the like, and has an aspheric image side surface.

In the zoom lens system according to Embodiment 2, the second lens unitG2, in order from the object side to the image side, comprises abi-concave fourth lens element L4, a bi-concave fifth lens element L5,and a positive meniscus sixth lens element L6 with the convex surfacefacing the object side. Among these, the fifth lens element L5 has anaspheric object side surface. The second lens unit G2 is a lens unithaving the greatest absolute value of optical power among all the lensunits, as shown in Numerical Example 2 described later. Also, the secondlens unit G2 is a lens unit having the greatest absolute value of awobbling value at a wide-angle limit among the focusing lens units, asshown in Numerical Example 2 described later.

In the zoom lens system according to Embodiment 2, the third lens unitG3, in order from the object side to the image side, comprises apositive meniscus seventh lens element L7 with the convex surface facingthe object side, a negative meniscus eighth lens element L8 with theconvex surface facing the object side, a positive meniscus ninth lenselement L9 with the convex surface facing the object side, a bi-convextenth lens element L10, and a negative meniscus eleventh lens elementL11 with the convex surface facing the image side. Among these, theeighth lens element L8 and the ninth lens element L9 are cemented witheach other, and the tenth lens element L10 and the eleventh lens elementL11 are cemented with each other. The ninth lens element L9 has anaspheric image side surface, and the tenth lens element L10 has anaspheric object side surface. Further, an aperture diaphragm A isprovided between the ninth lens element L9 and the tenth lens elementL10.

In the zoom lens system according to Embodiment 2, the fourth lens unitG4, in order from the object side to the image side, comprises anegative meniscus twelfth lens element L12 with the convex surfacefacing the object side, and a bi-concave thirteenth lens element L13.

In the zoom lens system according to Embodiment 2, the fifth lens unitG5 comprises solely a bi-convex fourteenth lens element L14. Thefourteenth lens element L14 has an aspheric image side surface.

In the zoom lens system according to Embodiment 2, the fourth lens unitG4 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 2, the tenth lenselement L10 and the eleventh lens element L11 in the third lens unit G3correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 2, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 and the fourth lens unit G4monotonically move to the image side, and the first lens unit G1, thethird lens unit G3, and the fifth lens unit G5 are fixed relative to theimage surface S. That is, in zooming, the second lens unit G2 and thefourth lens unit G4 individually move along the optical axis so that theinterval between the first lens unit G1 and the second lens unit G2 andthe interval between the third lens unit G3 and the fourth lens unit G4increase, and the interval between the second lens unit G2 and the thirdlens unit G3 and the interval between the fourth lens unit G4 and thefifth lens unit G5 decrease.

Further, in the zoom lens system according to Embodiment 2, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 does not move along theoptical axis at a wide-angle limit, but moves to the object side alongthe optical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the fourth lens unit G4 moves to the image sidealong the optical axis at a wide-angle limit, and moves to the objectside along the optical axis in other zooming conditions.

As shown in FIG. 9, in the zoom lens system according to Embodiment 3,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a bi-convex second lens element L2, anda positive meniscus third lens element L3 with the convex surface facingthe object side. Among these, the first lens element L1 and the secondlens element L2 are cemented with each other.

In the zoom lens system according to Embodiment 3, the second lens unitG2, in order from the object side to the image side, comprises apositive meniscus fourth lens element L4 with the convex surface facingthe image side, a bi-concave fifth lens element L5, a bi-concave sixthlens element L6, and a bi-convex seventh lens element L7. Among these,the fourth lens element L4 and the fifth lens element L5 are cementedwith each other. The fourth lens element L4 is an aspherical lenselement formed of a thin layer of resin or the like, and has an asphericobject side surface. The second lens unit G2 is a lens unit having thegreatest absolute value of optical power among all the lens units, asshown in Numerical Example 3 described later. Also, the second lens unitG2 is a lens unit having the greatest absolute value of a wobbling valueat a wide-angle limit among the focusing lens units, as shown inNumerical Example 3 described later.

In the zoom lens system according to Embodiment 3, the third lens unitG3, in order from the object side to the image side, comprises abi-convex eighth lens element L8, a negative meniscus ninth lens elementL9 with the convex surface facing the object side, and a bi-convex tenthlens element L10. Among these, the ninth lens element L9 and the tenthlens element L10 are cemented with each other. The eighth lens elementL8 has two aspheric surfaces.

In the zoom lens system according to Embodiment 3, the fourth lens unitG4, in order from the object side to the image side, comprises abi-convex eleventh lens element L11, and a negative meniscus twelfthlens element L12 with the convex surface facing the image side. Theeleventh lens element L11 and the twelfth lens element L12 are cementedwith each other. The eleventh lens element L11 has an asphericobject-side surface. Further, an aperture diaphragm A is provided on theobject side relative to the eleventh lens element L11.

In the zoom lens system according to Embodiment 3, the fifth lens unitG5, in order from the object side to the image side, comprises anegative meniscus thirteenth lens element L13 with the convex surfacefacing the object side, a bi-concave fourteenth lens element L14, abi-convex fifteenth lens element L15, and a bi-convex sixteenth lenselement L16. Among these, the fourteenth lens element L14 and thefifteenth lens element L15 are cemented with each other. The sixteenthlens element L16 has two aspheric surfaces.

In the zoom lens system according to Embodiment 3, the sixth lens unitG6 comprises solely a positive meniscus seventeenth lens element L17with the convex surface facing the object side. The seventeenth lenselement L17 has two aspheric surfaces.

In the zoom lens system according to Embodiment 3, the fifth lens unitG5 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 3, the eleventh lenselement L11 and the twelfth lens element L12 in the fourth lens unit G4correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 3, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 monotonically moves to the image side,the third lens unit G3 moves with locus of a convex to the object side,and the fifth lens unit G5 moves with locus of a convex to the imageside so that its position is closer to the image side at a telephotolimit than at a wide-angle limit. Further, the first lens unit G1, thefourth lens unit G4, and the sixth lens unit G6 are fixed relative tothe image surface S. That is, in zooming, the second lens unit G2, thethird lens unit G3, and the fifth lens unit G5 individually move alongthe optical axis so that the interval between the first lens unit G1 andthe second lens unit G2 and the interval between the fourth lens unit G4and the fifth lens unit G5 increase, and the interval between the secondlens unit G2 and the third lens unit G3 and the interval between thefifth lens unit G5 and the sixth lens unit G6 decrease.

Further, in the zoom lens system according to Embodiment 3, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 does not move along theoptical axis at a wide-angle limit, but moves to the object side alongthe optical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the fifth lens unit G5 moves to the image side alongthe optical axis at a wide-angle limit and at a telephoto limit, andmoves to the object side along the optical axis in other zoomingconditions.

As shown in FIG. 13, in the zoom lens system according to Embodiment 4,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a bi-convex second lens element L2, anda positive meniscus third lens element L3 with the convex surface facingthe object side. Among these, the first lens element L1 and the secondlens element L2 are cemented with each other.

In the zoom lens system according to Embodiment 4, the second lens unitG2, in order from the object side to the image side, comprises anegative meniscus fourth lens element L4 with the convex surface facingthe image side, a bi-concave fifth lens element L5, a bi-concave sixthlens element L6, and a bi-convex seventh lens element L7. Among these,the fourth lens element L4 and the fifth lens element L5 are cementedwith each other. The fourth lens element L4 is an aspherical lenselement formed of a thin layer of resin or the like, and has an asphericobject side surface. The second lens unit G2 is a lens unit having thegreatest absolute value of optical power among all the lens units, asshown in Numerical Example 4 described later. Also, the second lens unitG2 is a lens unit having the greatest absolute value of a wobbling valueat a wide-angle limit among the focusing lens units, as shown inNumerical Example 4 described later.

In the zoom lens system according to Embodiment 4, the third lens unitG3, in order from the object side to the image side, comprises abi-convex eighth lens element L8, a negative meniscus ninth lens elementL9 with the convex surface facing the object side, and a bi-convex tenthlens element L10. Among these, the ninth lens element L9 and the tenthlens element L10 are cemented with each other. The eighth lens elementL8 has two aspheric surfaces.

In the zoom lens system according to Embodiment 4, the fourth lens unitG4, in order from the object side to the image side, comprises abi-convex eleventh lens element L11, and a negative meniscus twelfthlens element L12 with the convex surface facing the image side. Theeleventh lens element L11 and the twelfth lens element L12 are cementedwith each other. The eleventh lens element L11 has an aspheric objectside surface. Further, an aperture diaphragm A is provided on the objectside relative to the eleventh lens element L11.

In the zoom lens system according to Embodiment 4, the fifth lens unitG5, in order from the object side to the image side, comprises anegative meniscus thirteenth lens element L13 with the convex surfacefacing the object side, a bi-concave fourteenth lens element L14, abi-convex fifteenth lens element L15, and a bi-convex sixteenth lenselement L16. Among these, the fourteenth lens element L14 and thefifteenth lens element L15 are cemented with each other. The sixteenthlens element L16 has two aspheric surfaces.

In the zoom lens system according to Embodiment 4, the sixth lens unitG6 comprises solely a positive meniscus seventeenth lens element L17with the convex surface facing the object side. The seventeenth lenselement L17 has two aspheric surfaces.

In the zoom lens system according to Embodiment 4, the fifth lens unitG5 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 4, the eleventh lenselement L11 and the twelfth lens element L12 in the fourth lens unit G4correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 4, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 monotonically moves to the image side,the third lens unit G3 moves with locus of a convex to the object side,and the fifth lens unit G5 moves with locus of a convex to the imageside so that its position is closer to the image side at a telephotolimit than at a wide-angle limit. Further, the first lens unit G1, thefourth lens unit G4, and the sixth lens unit G6 are fixed relative tothe image surface S. That is, in zooming, the second lens unit G2, thethird lens unit G3, and the fifth lens unit G5 individually move alongthe optical axis so that the interval between the first lens unit G1 andthe second lens unit G2 and the interval between the fourth lens unit G4and the fifth lens unit G5 increase, and the interval between the secondlens unit G2 and the third lens unit G3 and the interval between thefifth lens unit G5 and the sixth lens unit G6 decrease.

Further, in the zoom lens system according to Embodiment 4, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 does not move along theoptical axis at a wide-angle limit, but moves to the object side alongthe optical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the fifth lens unit G5 moves to the image side alongthe optical axis in all zooming conditions.

As shown in FIG. 17, in the zoom lens system according to Embodiment 5,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a bi-convex second lens element L2, anda bi-convex third lens element L3. Among these, the first lens elementL1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment 5, the second lens unitG2, in order from the object side to the image side, comprises anegative meniscus fourth lens element L4 with the convex surface facingthe object side, and a positive meniscus fifth lens element L5 with theconvex surface facing the object side. The fourth lens element L4 andthe fifth lens element L5 are cemented with each other. The second lensunit G2 is a lens unit having the greatest absolute value of a wobblingvalue at a wide-angle limit among the focusing lens units, as shown inNumerical Example 5 described later.

In the zoom lens system according to Embodiment 5, the third lens unitG3 comprises solely a bi-concave sixth lens element L6.

In the zoom lens system according to Embodiment 5, the fourth lens unitG4, in order from the object side to the image side, comprises abi-convex seventh lens element L7, a negative meniscus eighth lenselement L8 with the convex surface facing the object side, a positivemeniscus ninth lens element L9 with the convex surface facing the objectside, a bi-convex tenth lens element L10, and a negative meniscuseleventh lens element L11 with the convex surface facing the image side.Among these, the eighth lens element L8 and the ninth lens element L9are cemented with each other, and the tenth lens element L10 and theeleventh lens element L11 are cemented with each other. The seventh lenselement L7 has two aspheric surfaces, and the tenth lens element L10 hasan aspheric object side surface. Further, an aperture diaphragm A isprovided between the seventh lens element L7 and the eighth lens elementL8.

In the zoom lens system according to Embodiment 5, the fifth lens unitG5, in order from the object side to the image side, comprises anegative meniscus twelfth lens element L12 with the convex surfacefacing the object side, a bi-concave thirteenth lens element L13, abi-convex fourteenth lens element L14, and a negative meniscus fifteenthlens element L15 with the convex surface facing the object side. Amongthese, the thirteenth lens element L13 and the fourteenth lens elementL14 are cemented with each other. The fifth lens unit G5 is a lens unithaving the greatest absolute value of optical power among all the lensunits, as shown in Numerical Example 5 described later.

In the zoom lens system according to Embodiment 5, the sixth lens unitG6 comprises solely a positive meniscus sixteenth lens element L16 withthe convex surface facing the object side.

In the zoom lens system according to Embodiment 5, the fifth lens unitG5 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 5, the tenth lenselement L10 and the eleventh lens element L11 in the fourth lens unit G4correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 5, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 and the third lens unit G3 monotonicallymove to the image side, and the fifth lens unit G5 moves to the objectside with locus of a convex to the image side. The first lens unit G1,the fourth lens unit G4, and the sixth lens unit G6 are fixed relativeto the image surface S. That is, in zooming, the second lens unit G2,the third lens unit G3, and the fifth lens unit G5 individually movealong the optical axis so that the interval between the first lens unitG1 and the second lens unit G2 and the interval between the fifth lensunit G5 and the sixth lens unit G6 increase, and the interval betweenthe third lens unit G3 and the fourth lens unit G4 and the intervalbetween the fourth lens unit G4 and the fifth lens unit G5 decrease.

Further, in the zoom lens system according to Embodiment 5, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 moves to the object sidealong the optical axis at a telephoto limit, but does not move along theoptical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the third lens unit G3 moves to the object sidealong the optical axis in all zooming conditions. Further, at the timeof focusing from the infinity in-focus condition to the close-objectin-focus condition, the fifth lens unit G5 does not move along theoptical axis at a wide-angle limit, but moves to the image side alongthe optical axis in other zooming conditions.

As shown in FIG. 21, in the zoom lens system according to Embodiment 6,the first lens unit G1, in order from the object side to the image side,comprises a negative meniscus first lens element L1 with the convexsurface facing the object side, a bi-convex second lens element L2, anda bi-convex third lens element L3. Among these, the first lens elementL1 and the second lens element L2 are cemented with each other.

In the zoom lens system according to Embodiment 6, the second lens unitG2, in order from the object side to the image side, comprises anegative meniscus fourth lens element L4 with the convex surface facingthe object side, and a positive meniscus fifth lens element L5 with theconvex surface facing the object side. The fourth lens element L4 andthe fifth lens element L5 are cemented with each other. The second lensunit G2 is a lens unit having the greatest absolute value of a wobblingvalue at a wide-angle limit among the focusing lens units, as shown inNumerical Example 6 described later.

In the zoom lens system according to Embodiment 6, the third lens unitG3 comprises solely a bi-concave sixth lens element L6.

In the zoom lens system according to Embodiment 6, the fourth lens unitG4, in order from the object side to the image side, comprises abi-convex seventh lens element L7, a negative meniscus eighth lenselement L8 with the convex surface facing the object side, a positivemeniscus ninth lens element L9 with the convex surface facing the objectside, a bi-convex tenth lens element L10, and a negative meniscuseleventh lens element L11 with the convex surface facing the image side.Among these, the eighth lens element L8 and the ninth lens element L9are cemented with each other, and the tenth lens element L10 and theeleventh lens element L11 are cemented with each other. The seventh lenselement L7 has two aspheric surfaces, and the tenth lens element L10 hasan aspheric object side surface. Further, an aperture diaphragm A isprovided between the seventh lens element L7 and the eighth lens elementL8.

In the zoom lens system according to Embodiment 6, the fifth lens unitG5, in order from the object side to the image side, comprises anegative meniscus twelfth lens element L12 with the convex surfacefacing the object side, a bi-concave thirteenth lens element L13, abi-convex fourteenth lens element L14, and a negative meniscus fifteenthlens element L15 with the convex surface facing the object side. Amongthese, the thirteenth lens element L13 and the fourteenth lens elementL14 are cemented with each other. The fifth lens unit G5 is a lens unithaving the greatest absolute value of optical power among all the lensunits, as shown in Numerical Example 6 described later.

In the zoom lens system according to Embodiment 6, the sixth lens unitG6 comprises solely a positive meniscus sixteenth lens element L16 withthe convex surface facing the object side.

In the zoom lens system according to Embodiment 6, the fifth lens unitG5 corresponds to a wobbling lens unit described later, which senses amoving direction of the focusing lens units at the time of focusing bywobbling itself in a direction along the optical axis.

In the zoom lens system according to Embodiment 6, the tenth lenselement L10 and the eleventh lens element L11 in the fourth lens unit G4correspond to an image blur compensating lens unit described later,which moves in a direction perpendicular to the optical axis in order tooptically compensate image blur.

In the zoom lens system according to Embodiment 6, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the second lens unit G2 and the third lens unit G3 monotonicallymove to the image side, and the fifth lens unit G5 moves to the objectside with locus of a convex to the image side. The first lens unit G1,the fourth lens unit G4, and the sixth lens unit G6 are fixed relativeto the image surface S. That is, in zooming, the second lens unit G2,the third lens unit G3, and the fifth lens unit G5 individually movealong the optical axis so that the interval between the first lens unitG1 and the second lens unit G2 and the interval between the fifth lensunit G5 and the sixth lens unit G6 increase, and the interval betweenthe third lens unit G3 and the fourth lens unit G4 and the intervalbetween the fourth lens unit G4 and the fifth lens unit G5 decrease.

Further, in the zoom lens system according to Embodiment 6, at the timeof focusing from an infinity in-focus condition to a close-objectin-focus condition, the second lens unit G2 moves to the object sidealong the optical axis at a telephoto limit, but does not move along theoptical axis in other zooming conditions. Further, at the time offocusing from the infinity in-focus condition to the close-objectin-focus condition, the third lens unit G3 moves to the object sidealong the optical axis in all zooming conditions. Further, at the timeof focusing from the infinity in-focus condition to the close-objectin-focus condition, the fifth lens unit G5 does not move along theoptical axis at a wide-angle limit, but moves to the image side alongthe optical axis in other zooming conditions.

The zoom lens systems according to Embodiments 1 to 6 are each providedwith a plurality of movable lens units which individually move along theoptical axis at the time of zooming from a wide-angle limit to atelephoto limit during image taking. In the zoom lens systems accordingto Embodiments 1 to 6, at least two of the movable lens units arefocusing lens units which move along the optical axis at the time offocusing from an infinity in-focus condition to a close-object in-focuscondition in at least one zooming position from a wide-angle limit to atelephoto limit, and among the focusing lens units, a lens unit havingthe absolute value, which is not the greatest absolute value, of awobbling value at a wide-angle limit behaves as a wobbling lens unitwhich senses a moving direction of the focusing lens units at the timeof focusing by wobbling itself in a direction along the optical axis.

Among the camera systems, a video camera system for image taking ofvideos is provided with a zoom lens system which is able to continuoushigh-speed autofocus. In the case that continuous autofocus is carriedout at a high-speed in a zoom lens system, in general, a focusing lensunit is wobbled (wobbling action) in a direction along the optical axisat a high-speed, which results in preparation of a series of conditions,i.e., “non-focus condition” to “in-focus condition” to “non-focuscondition”. Then, signal elements at the frequency range where imageareas partially exist are detected from output signals of an imagesensor, and the most preferable position of the focusing lens unit forin-focus condition is determined. Then, the focusing lens unit is movedto the most preferable position. A series of these actions is repeated.

In the case that the wobbling action is carried out, in general, a focallength of the entire system varies due to wobbling of the focusing lensunit in a direction along the optical axis. As a result, image sizecorresponding to the subject, i.e., image taking magnification varies.When variation in the image taking magnification due to wobbling isgreat, feeling of strangeness is caused.

On the other hand, in the zoom lens systems according to Embodiments 1to 6, among the plurality of focusing lens units, a lens unit having theabsolute value, which is not the greatest absolute value, of a wobblingvalue at a wide-angle limit wobbles as the wobbling lens unit in adirection along the optical axis. Therefore, in the zoom lens systemsaccording to Embodiments 1 to 6, variation in image taking magnificationdue to wobbling is suppressed in spite of continuous high-speedautofocusing performance, which results in no giving a user feeling ofstrangeness.

In the present invention, the wobbling value at a wide-angle limit isthe value represented by the following expression (a).

W=1/e+β _(WO)/(Sb×f _(WO))−1/((β_(R) ×f _(R))  (a)

where

W is a wobbling value at a wide-angle limit (wobbling incrementalmagnification sensitivity),

Sb is a focus sensitivity of the wobbling lens unit represented by thefollowing expression

Sb=(1−β_(WO) ²)×β_(R) ²,

e is an exit pupil position of the entire system at a wide-angle limit,

β_(WO) is a paraxial lateral magnification of the wobbling lens unit ata wide-angle limit in an infinity in-focus condition,

f_(WO) is a focal length of the wobbling lens unit at a wide-angle limitin an infinity in-focus condition,

β_(R) is a paraxial lateral magnification of a system on the image siderelative to the wobbling lens unit at a wide-angle limit in an infinityin-focus condition, and

f_(R) is a focal length of a system on the image side relative to thewobbling lens unit at a wide-angle limit in an infinity in-focuscondition.

In the zoom lens systems according to Embodiments 1 to 6, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the lens unit located closest to the object side, i.e., thefirst lens unit G1, is fixed relative to the image surface. Therefore,weight reduction of the movable lens units is achieved, and therebyactuators can be arranged inexpensively. In addition, generation ofnoise during zooming is suppressed. Moreover, since the overall lengthof lens system is not changed, a user can easily operate the lenssystem, and entry of dust or the like into the lens system issufficiently prevented.

In the zoom lens systems according to Embodiments 1 to 6, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the lens unit having the aperture diaphragm, i.e., the thirdlens unit G3 in Embodiments 1 and 2 or the fourth lens unit G4 inEmbodiments 3 to 6, is fixed relative to the image surface. Therefore,the unit including the lens unit having the aperture diaphragm which isheavy in weight is not moved, and thereby the actuators can be arrangedinexpensively.

In the zoom lens systems according to Embodiments 1 to 6, at the time ofzooming from a wide-angle limit to a telephoto limit during imagetaking, the lens unit located closest to the image side, i.e., the fifthlens unit G5 in Embodiments 1 and 2 or the sixth lens unit G6 inEmbodiments 3 to 6, is fixed relative to the image surface. Therefore,entry of dust or the like into the lens system is sufficientlyprevented.

In the zoom lens systems according to Embodiments 1 to 6, the lens unitlocated closest to the object side, i.e., the first lens unit G1, haspositive optical power. Therefore, the size of the lens system isreduced. In addition, the amount of aberration caused by decentering oflens elements is reduced.

In the zoom lens systems according to Embodiments 1 to 6, at the time offocusing from an infinity in-focus condition to a close-object in-focuscondition in the same zooming position from a wide-angle limit to atelephoto limit during image taking, the ratio of an amount of movementof a focusing lens unit α, which is one of the focusing lens units, toan amount of movement of a focusing lens unit β, which is one of thefocusing lens units and is different from the focusing lens unit α, isconstant regardless of the object distance. Therefore, focusing controlis facilitated.

In the zoom lens systems according to Embodiments 1 to 4, the aperturediaphragm is included in the lens unit which is located having two airspaces toward the image side from the lens unit that is located closestto the object side, i.e., in the third lens unit G3, or the aperturediaphragm is located on the image side relative to of the third lensunit G3. Therefore, the aperture diameter is reduced, and thereby theunit size of the aperture diaphragm is reduced. In addition, since noaperture diaphragm is located on the object side relative to the thirdlens unit G3, the second lens unit G2 and the third lens unit G3 can bemoved close to each other at a telephoto limit, and thus aberrationcompensation at the telephoto limit is facilitated. Furthermore, sincethe unit of the aperture diaphragm, which tends to have a largediameter, is located apart from the second lens unit G2, the actuator ofthe second lens unit G2 is easily arranged, and size reduction isachieved in the diameter direction of the lens barrel.

The zoom lens systems according to Embodiments 1 to 6 are each providedwith an image blur compensating lens unit which moves in a directionperpendicular to the optical axis. The image blur compensating lens unitcompensates image point movement caused by vibration of the entiresystem, that is, optically compensates image blur caused by handblurring, vibration and the like.

When image point movement caused by vibration of the entire system is tobe compensated, the image blur compensating lens unit moves in thedirection perpendicular to the optical axis, so that image blur iscompensated in a state that size increase in the entire zoom lens systemis suppressed to realize a compact construction and that excellentimaging characteristics such as small decentering coma aberration andsmall decentering astigmatism are satisfied.

The image blur compensating lens unit according to the present inventionmay be a single lens unit. If a single lens unit is composed of aplurality of lens elements, the image blur compensating lens unit may beany one lens element or a plurality of adjacent lens elements among theplurality of lens elements.

The zoom lens systems according to Embodiments 1 and 2 have a five-unitconstruction including first to fifth lens units G1 to G5, and the zoomlens systems according to Embodiments 3 to 6 have a six-unitconstruction including first to sixth lens units G1 to G6. In thepresent invention, however, the number of lens units constituting thezoom lens system is not particularly limited so long as the zoom lenssystem includes a plurality of movable lens units, at least two of themovable lens units are focusing lens units, and among the focusing lensunits, a lens unit having the absolute value, which is not the greatestabsolute value, of a wobbling value. Further, the optical powers of therespective lens units constituting the zoom lens system are notparticularly limited.

The following description is given for conditions preferred to besatisfied by a zoom lens system like the zoom lens systems according toEmbodiments 1 to 6. Here, a plurality of preferable conditions are setforth for the zoom lens system according to each embodiment. Aconstruction that satisfies all the plurality of conditions is mostdesirable for the zoom lens system. However, when an individualcondition is satisfied, a zoom lens system having the correspondingeffect is obtained.

For example, in a zoom lens system like the zoom lens systems accordingto Embodiments 1 to 6, which includes a plurality of lens units eachcomprising at least one lens element, in which the plurality of lensunits include a plurality of movable lens units individually movingalong the optical axis at the time of zooming from a wide-angle limit toa telephoto limit during image taking, in which at least two of themovable lens units are focusing lens units which move along the opticalaxis at the time of focusing from an infinity in-focus condition to aclose-object in-focus condition in at least one zooming position from awide-angle limit to a telephoto limit, and in which among the focusinglens units, a lens unit having the absolute value, which is not thegreatest absolute value, of a wobbling value at a wide-angle limitrepresented by the above-described expression (a) is a wobbling lensunit which senses a moving direction of the focusing lens units at thetime of focusing by wobbling itself in a direction along the opticalaxis (this lens configuration is referred to as a basic configuration ofthe embodiments, hereinafter), the following condition (1) is preferablysatisfied.

0.1<T ₁ /f _(W)<1.5  (1)

where

T₁ is an axial thickness of the lens unit located closest to the objectside, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (1) sets forth the relationship between the axialthickness of the lens unit located closest to the object side, i.e., thefirst lens unit, and the focal length of the entire system at thewide-angle limit. When the value goes below the lower limit of thecondition (1), the optical power of the first lens unit cannot beincreased, and then the size of the zoom lens system might be increased.On the other hand, when the value exceeds the upper limit of thecondition (1), the thickness of the first lens unit is increased, whichalso might result in an increase in the size of the zoom lens system.

When at least one of the following conditions (1)′ and (1)″ issatisfied, the above-mentioned effect is achieved more successfully.

0.17<T ₁ /f _(W)  (1)′

T ₁ /f _(W)<1.20  (1)″

For example, a zoom lens system having the basic configuration like thezoom lens systems according to Embodiments 1 to 6 preferably satisfiesthe following condition (2).

0.1<(T ₁ +T ₂)/f _(W)<2.5  (2)

where

T₁ is an axial thickness of the lens unit located closest to the objectside,

T₂ is an axial thickness of a lens unit which is located having one airspace toward the image side from the lens unit located closest to theobject side, and

f_(W) is a focal length of the entire system at a wide-angle limit.

The condition (2) sets forth the relationship between the sum of theaxial thickness of the lens unit located closest to the object side,i.e., the first lens unit, and the axial thickness of the lens unitlocated just on the image side of the first lens unit, i.e., the secondlens unit, and the focal length of the entire system at a wide-anglelimit. When the value goes below the lower limit of the condition (2),the optical powers of the lens units cannot be increased, and then thesize of the zoom lens system might be increased. On the other hand, whenthe value exceeds the upper limit of the condition (2), the thicknessesof the lens units are increased. Also in this case, the size of the zoomlens system might be increased.

When at least one of the condition (2)′-1 or (2)′-2 and the condition(2)″-1 or (2)″-2 is satisfied, the above-mentioned effect is achievedmore successfully.

0.20<(T ₁ +T ₂)/f _(W)  (2)′-1

0.25<(T ₁ +T ₂)/f _(W)  (2)′-2

(T ₁ +T ₂)/f _(W)<2.0  (2)″-1

(T ₁ +T ₂)/f _(W)<1.5  (2)″-2

The individual lens units constituting the zoom lens systems accordingto Embodiments 1 to 6 are each composed exclusively of refractive typelens elements that deflect incident light by refraction (that is, lenselements of a type in which deflection is achieved at the interfacebetween media having different refractive indices). However, the presentinvention is not limited to this construction. For example, the lensunits may employ diffractive type lens elements that deflect incidentlight by diffraction; refractive-diffractive hybrid type lens elementsthat deflect incident light by a combination of diffraction andrefraction; or gradient index type lens elements that deflect incidentlight by distribution of refractive index in the medium. In particular,in the refractive-diffractive hybrid type lens element, when adiffraction structure is formed in the interface between media havingdifferent refractive indices, wavelength dependence of the diffractionefficiency is improved. Thus, such a configuration is preferable.

Embodiment 7

FIG. 25 is a schematic construction diagram of an interchangeable-lenstype digital camera system according to Embodiment 7.

The interchangeable-lens type digital camera system 100 according toEmbodiment 7 includes a camera body 101, and an interchangeable lensapparatus 201 which is detachably connected to the camera body 101.

The camera body 101 includes: an image sensor 102 which receives anoptical image formed by a zoom lens system 202 of the interchangeablelens apparatus 201, and converts the optical image into an electricimage signal; a liquid crystal monitor 103 which displays the imagesignal obtained by the image sensor 102; and a camera mount section 104.On the other hand, the interchangeable lens apparatus 201 includes: azoom lens system 202 according to any of Embodiments 1 to 6; a lensbarrel 203 which holds the zoom lens system 202; and a lens mountsection 204 connected to the camera mount section 104 of the camera body101. The camera mount section 104 and the lens mount section 204 arephysically connected to each other. Moreover, the camera mount section104 and the lens mount section 204 function as interfaces which allowthe camera body 101 and the interchangeable lens apparatus 201 toexchange signals, by electrically connecting a controller (not shown) inthe camera body 101 and a controller (not shown) in the interchangeablelens apparatus 201. In FIG. 25, the zoom lens system according toEmbodiment 1 is employed as the zoom lens system 202.

In Embodiment 7, since the zoom lens system 202 according to any ofEmbodiments 1 to 6 is employed, a compact interchangeable lens apparatushaving excellent imaging performance can be realized at low cost.Moreover, size reduction and cost reduction of the entire camera system100 according to Embodiment 7 can be achieved. In the zoom lens systemsaccording to Embodiments 1 to 6, the entire zooming range need not beused. That is, in accordance with a desired zooming range, a range wheresatisfactory optical performance is obtained may exclusively be used.Then, the zoom lens system may be used as one having a lowermagnification than the zoom lens systems described in Embodiments 1 to6.

Numerical examples are described below in which the zoom lens systemsaccording to Embodiments 1 to 6 are implemented. Here, in the numericalexamples, the units of length are all “mm”, while the units of viewangle are all “°”. Moreover, in the numerical examples, r is the radiusof curvature, d is the axial distance, nd is the refractive index to thed-line, and vd is the Abbe number to the d-line. In the numericalexamples, the surfaces marked with * are aspherical surfaces, and theaspherical surface configuration is defined by the following expression.

$Z = {\frac{h^{2}/r}{1 + \sqrt{1 - {( {1 + \kappa} )( {h/r} )^{2}}}} + {\sum{A_{n}h^{n}}}}$

Here, the symbols in the formula indicate the following quantities.

Z is a distance from a point on an aspherical surface at a height hrelative to the optical axis to a tangential plane at the vertex of theaspherical surface,

h is a height relative to the optical axis,

r is a radius of curvature at the top,

κ is a conic constant, and

An is a n-th order aspherical coefficient.

FIGS. 2, 6, 10, 14, 18, and 22 are longitudinal aberration diagrams ofan infinity in-focus condition of the zoom lens systems according toEmbodiments 1 to 6, respectively.

FIGS. 3, 7, 11, 15, 19, and 23 are longitudinal aberration diagrams of aclose-object in-focus condition of the zoom lens systems according toEmbodiments 1 to 6, respectively. In Examples 1 and 2, the objectdistance is 896 mm. In Examples 3 and 4, the object distance is 854 mm.In Examples 5 and 6, the object distance is 881 mm.

In each longitudinal aberration diagram, part (a) shows the aberrationat a wide-angle limit, part (b) shows the aberration at a middleposition, and part (c) shows the aberration at a telephoto limit. Eachlongitudinal aberration diagram, in order from the left-hand side, showsthe spherical aberration (SA (mm)), the astigmatism (AST (mm)) and thedistortion (DIS (%)). In each spherical aberration diagram, the verticalaxis indicates the F-number (in each Fig., indicated as F), and thesolid line, the short dash line and the long dash line indicate thecharacteristics to the d-line, the F-line and the C-line, respectively.In each astigmatism diagram, the vertical axis indicates the imageheight (in each Fig., indicated as H), and the solid line and the dashline indicate the characteristics to the sagittal plane (in each Fig.,indicated as “s”) and the meridional plane (in each Fig., indicated as“m”), respectively. In each distortion diagram, the vertical axisindicates the image height (in each Fig., indicated as H).

FIGS. 4, 8, 12, 16, 20, and 24 are lateral aberration diagrams of thezoom lens systems at a telephoto limit according to Embodiments 1 to 6,respectively.

In each lateral aberration diagram, the aberration diagrams in the upperthree parts correspond to a basic state where image blur compensation isnot performed at a telephoto limit, while the aberration diagrams in thelower three parts correspond to an image blur compensation state wherethe image blur compensating lens unit (Examples 1 and 2: the tenth lenselement L10 and the eleventh lens element L11 in the third lens unit G3,Examples 3 and 4: the eleventh lens element L11 and the twelfth lenselement L12 in the fourth lens unit G4, Examples 5 and 6: the tenth lenselement L10 and the eleventh lens element L11 in the fourth lens unitG4) is moved by a predetermined amount in a direction perpendicular tothe optical axis at a telephoto limit. Among the lateral aberrationdiagrams of a basic state, the upper part shows the lateral aberrationat an image point of 70% of the maximum image height, the middle partshows the lateral aberration at the axial image point, and the lowerpart shows the lateral aberration at an image point of −70% of themaximum image height. Among the lateral aberration diagrams of an imageblur compensation state, the upper part shows the lateral aberration atan image point of 70% of the maximum image height, the middle part showsthe lateral aberration at the axial image point, and the lower partshows the lateral aberration at an image point of −70% of the maximumimage height. In each lateral aberration diagram, the horizontal axisindicates the distance from the principal ray on the pupil surface, andthe solid line, the short dash line and the long dash line indicate thecharacteristics to the d-line, the F-line and the C-line, respectively.In each lateral aberration diagram, the meridional plane is adopted asthe plane containing the optical axis of the first lens unit G1 and theoptical axis of the third lens unit G3 (Examples 1 and 2) or the planecontaining the optical axis of the first lens unit G1 and the opticalaxis of the fourth lens unit G4 (Examples 3 to 6).

In the zoom lens system according to each example, the amount ofmovement of the image blur compensating lens unit in a directionperpendicular to the optical axis in the image blur compensation stateat a telephoto limit is as follows.

Example 1 0.234 mm Example 2 0.264 mm Example 3 0.500 mm Example 4 0.500mm Example 5 0.500 mm Example 6 0.500 mm

When the shooting distance is infinity, at a telephoto limit, the amountof image decentering in a case that the zoom lens system inclines by0.3° is equal to the amount of image decentering in a case that theimage blur compensating lens unit displaces in parallel by each of theabove-mentioned values in a direction perpendicular to the optical axis.

As seen from the lateral aberration diagrams, satisfactory symmetry isobtained in the lateral aberration at the axial image point. Further,when the lateral aberration at the +70% image point and the lateralaberration at the −70% image point are compared with each other in thebasic state, all have a small degree of curvature and almost the sameinclination in the aberration curve. Thus, decentering coma aberrationand decentering astigmatism are small. This indicates that sufficientimaging performance is obtained even in the image blur compensationstate. Further, when the image blur compensation angle of a zoom lenssystem is the same, the amount of parallel translation required forimage blur compensation decreases with decreasing focal length of theentire zoom lens system. Thus, at arbitrary zoom positions, sufficientimage blur compensation can be performed for image blur compensationangles up to 0.3° without degrading the imaging characteristics.

Numerical Example 1

The zoom lens system of Numerical Example 1 corresponds to Embodiment 1shown in FIG. 1. Table 1 shows the surface data of the zoom lens systemof Numerical Example 1. Table 2 shows the aspherical data. Table 3 showsvarious data in an infinity in-focus condition. Table 4 shows variousdata in a close-object in-focus condition. Table 5 shows the wobblingvalues of the focusing lens units.

TABLE 1 (Surface data) Surface number r d nd vd Object surface ∞  139.45910 1.20000 1.84666 23.8  2 25.10580 8.22430 1.72916 54.7  37500.52950 0.13520 1.51340 52.9  4* −1133.51480 Variable  5 −209.702400.90000 1.91082 35.2  6 12.86870 3.66440  7* −26.10780 1.20000 1.6940056.3  8 29.71090 0.15000  9 23.69790 2.19550 1.94595 18.0 10 542.52450Variable 11 14.60210 2.82520 1.67270 32.2 12 69.38020 0.35860 1319.37730 0.60000 1.90366 31.3 14 9.13140 3.52070 1.52500 70.3  15*149.33540 1.68510 16 ∞ 3.50000 (Diaphragm)  17* 24.57900 3.02250 1.5067070.5 18 −13.43620 0.50000 1.80518 25.5 19 −20.61450 Variable 20 29.284800.60000 1.83481 42.7 21 11.74650 1.60420 22 −28.70330 0.60000 1.6180063.4 23 170.95130 Variable 24 21.32440 6.55150 1.52500 70.3  25*−48.46490 (BF) Image surface ∞

TABLE 2 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 =1.66434E−06, A6 = −6.25080E−10, A8 = −8.58592E−13 A10 = 2.10796E−15Surface No. 7 K = 0.00000E+00, A4 = 1.23343E−05, A6 = −2.55507E−08, A8 =0.00000E+00 A10 = 0.00000E+00 Surface No. 15 K = 0.00000E+00, A4 =5.72394E−05, A6 = 1.91936E−07, A8 = 0.00000E+00 A10 = 0.00000E+00Surface No. 17 K = 0.00000E+00, A4 = −2.70227E−05, A6 = 8.68997E−08, A8= 0.00000E+00 A10 = 0.00000E+00 Surface No. 25 K = 0.00000E+00, A4 =2.87186E−05, A6 = −2.31449E−08, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE 3 (Various data in an infinity in-focus condition) Zooming ratio4.70869 Wide-angle Middle Telephoto limit position limit Focal length17.5100 37.9858 82.4491 F-number 3.60539 5.15110 5.76896 View angle35.0441 15.6249 7.1321 Image height 10.8150 10.8150 10.8150 Overalllength 102.57 102.57 102.57 of lens system BF 14.95 14.95 14.95 d41.1575 14.4071 24.3763 d10 24.2188 10.9692 1.0000 d19 3.1000 7.646413.7120 d23 16.1054 11.5590 5.4934 Zoom lens unit data Lens InitialFocal unit surface No. length 1 1 58.05428 2 5 −11.29703 3 11 16.80424 420 −14.57985 5 24 29.14870

TABLE 4 (Various data in a close-object in-focus condition) Zoomingratio 3.48510 Wide-angle Middle Telephoto limit position limit Objectdistance 896.0000 896.0000 896.0000 Focal length 17.5193 31.0704 61.0564F-number 3.61754 5.02920 5.71191 View angle 34.9294 19.0037 9.0365 Imageheight 10.8150 10.8150 10.8150 Overall length 102.57 102.57 102.57 oflens system BF 14.95 14.95 14.95 d4 1.1575 11.4071 21.3764 d10 24.218813.9692 4.0000 d19 3.1781 6.5689 12.9874 d23 16.0273 12.6365 6.2181 Zoomlens unit data Lens Initial Focal unit surface No. length 1 1 58.05428 25 −11.29703 3 11 16.80424 4 20 −14.57985 5 24 29.14870

TABLE 5 (Wobbling values) Second Fourth lens unit lens unit W 0.042−0.007 Sb 1.010 −4.290 e −175.445 −175.445 β_(WO) −0.287 5.523 f_(WO)−11.297 −14.580 β_(R) −1.049 0.381 f_(R) 42.619 29.149

Numerical Example 2

The zoom lens system of Numerical Example 2 corresponds to Embodiment 2shown in FIG. 5. Table 6 shows the surface data of the zoom lens systemof Numerical Example 2. Table 7 shows the aspherical data. Table 8 showsvarious data in an infinity in-focus condition. Table 9 shows variousdata in a close-object in-focus condition. Table 10 shows the wobblingvalues of the focusing lens units.

TABLE 6 (Surface data) Surface number r d nd vd Object surface ∞  140.55390 1.20000 1.84666 23.8  2 25.48970 7.82810 1.72916 54.7  3−1060.14520 0.13160 1.51340 52.9  4* −518.58960 Variable  5 −129.075100.90000 1.91082 35.2  6 13.78230 3.43320  7* −26.13710 1.20000 1.6940056.3  8 30.86700 0.15000  9 24.83930 2.15460 1.94595 18.0 10 2103.46990Variable 11 14.42110 2.90810 1.67270 32.2 12 58.13430 0.23740 1318.93180 0.60000 1.90366 31.3 14 8.97480 3.83440 1.52500 70.3  15*486.06320 1.61730 16 ∞ 3.50000 (Diaphragm)  17* 25.82680 2.96730 1.5067070.5 18 −14.81600 0.50000 1.80518 25.5 19 −22.70770 Variable 20 28.944600.60000 1.83481 42.7 21 11.73350 1.61060 22 −32.94690 0.60000 1.6180063.4 23 94.79190 Variable 24 21.50100 6.42320 1.52500 70.3  25*−53.44240 (BF) Image surface ∞

TABLE 7 (Aspherical data) Surface No. 4 K = 0.00000E+00, A4 =1.69282E−06, A6 = −6.45222E−10, A8 = −7.25840E−13 A10 = 1.66047E−15Surface No. 7 K = 0.00000E+00, A4 = 1.13469E−05, A6 = −1.45516E−08, A8 =0.00000E+00 A10 = 0.00000E+00 Surface No. 15 K = 0.00000E+00, A4 =5.67011E−05, A6 = 1.26088E−07, A8 = 0.00000E+00 A10 = 0.00000E+00Surface No. 17 K = 0.00000E+00, A4 = −2.30451E−05, A6 = 6.87297E−08, A8= 0.00000E+00 A10 = 0.00000E+00 Surface No. 25 K = 0.00000E+00, A4 =2.52997E−05, A6 = −2.17080E−08, A8 = 0.00000E+00 A10 = 0.00000E+00

TABLE 8 (Various data in an infinity in-focus condition) Zooming ratio4.70878 Wide-angle Middle Telephoto limit position limit Focal length18.5399 40.2212 87.3004 F-number 3.60532 5.15004 5.76901 View angle33.5303 14.7707 6.7396 Image height 10.8150 10.8150 10.8150 Overalllength 102.57 102.57 102.57 of lens system BF 14.95 14.95 14.95 d41.2101 14.5172 24.6148 d10 24.4044 11.0972 1.0000 d19 3.1000 7.565413.0748 d23 16.5086 12.0435 6.5339 Zoom lens unit data Lens InitialFocal unit surface No. length 1 1 57.41235 2 5 −11.65482 3 11 16.91533 420 −14.59491 5 24 30.09227

TABLE 9 (Various data in a close-object in-focus condition) Zoomingratio 3.47845 Wide-angle Middle Telephoto limit position limit Objectdistance 896.0000 896.0000 896.0000 Focal length 18.5448 32.9026 64.5072F-number 3.61839 5.03658 5.74812 View angle 33.4016 17.9643 8.4812 Imageheight 10.8150 10.8150 10.8150 Overall length 102.57 102.57 102.57 oflens system BF 14.95 14.95 14.95 d4 1.2101 11.5172 21.6149 d10 24.404514.0972 4.0000 d19 3.1837 6.5548 12.7824 d23 16.4249 13.0542 6.8264 Zoomlens unit data Lens Initial Focal unit surface No. length 1 1 57.41235 25 −11.65482 3 11 16.91533 4 20 −14.59491 5 24 30.09227

TABLE 10 (Wobbling values) Second Fourth lens unit lens unit W 0.040−0.007 Sb 1.049 −4.488 e −156.903 −156.903 β_(WO) −0.301 5.385 f_(WO)−11.655 −14.595 β_(R) −1.074 0.400 f_(R) 42.498 30.092

Numerical Example 3

The zoom lens system of Numerical Example 3 corresponds to Embodiment 3shown in FIG. 9. Table 11 shows the surface data of the zoom lens systemof Numerical Example 3. Table 12 shows the aspherical data. Table 13shows various data in an infinity in-focus condition. Table 14 showsvarious data in a close-object in-focus condition. Table 15 shows thewobbling values of the focusing lens units.

TABLE 11 (Surface data) Surface number r d nd vd Object surface ∞  178.87740 1.50000 1.84666 23.8  2 51.11990 8.20570 1.49700 81.6  3−309.84050 0.15000  4 46.93030 4.87270 1.61800 63.4  5 153.26660Variable  6* −78.16680 0.30000 1.51340 52.9  7 −69.05600 1.05000 1.8830040.8  8 14.60860 4.08700  9 −26.25860 0.80000 1.72916 54.7 10 54.966700.15000 11 32.57540 2.29090 1.94595 18.0 12 −229.68230 Variable  13*17.10270 3.86620 1.68893 31.1  14* −252.13690 1.83550 15 78.948600.80000 1.85014 30.1 16 11.50760 4.28010 1.49700 81.6 17 −128.66160Variable 18 ∞ 3.50000 (Diaphragm)  19* 31.40570 3.09850 1.55332 71.7 20−22.99450 0.60000 1.80518 25.5 21 −38.08840 Variable 22 23.56040 0.600001.83481 42.7 23 12.02380 2.64670 24 −15.50110 0.60000 1.80420 46.5 25309.52360 2.10930 1.78472 25.7 26 −40.59840 0.15000  27* 40.416303.01540 1.53110 56.0  28* −46.21370 Variable  29* 21.44480 4.848301.50670 70.5  30* 186.74310 (BF) Image surface ∞

TABLE 12 (Aspherical data) Surface No. 6 K = 0.00000E+00, A4 =1.93253E−05, A6 = −3.16908E−08, A8 = −6.40929E−10 A10 = 3.54689E−12, A12= 2.66112E−24, A14 = −2.02843E−28 Surface No. 13 K = 0.00000E+00, A4 =−9.80366E−06, A6 = 1.05306E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 14 K = 0.00000E+00, A4 =1.02788E−05, A6 = 1.48632E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 19 K = 0.00000E+00, A4 =−8.80224E−06, A6 = 3.58312E−08, A8 = −8.16452E−10 A10 = 1.02445E−11, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 27 K = 0.00000E+00, A4 =4.18434E−05, A6 = 1.14558E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 28 K = 0.00000E+00, A4 =1.29529E−05, A6 = 1.47395E−07, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 29 K = 0.00000E+00, A4 =9.80214E−06, A6 = −1.00950E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 30 K = 0.00000E+00, A4 =3.88774E−05, A6 = −6.79912E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00

TABLE 13 (Various data in an infinity in-focus condition) Zooming ratio9.41751 Wide-angle Middle Telephoto limit position limit Focal length17.5100 53.7443 164.9003 F-number 3.60518 4.94428 5.76897 View angle35.0198 11.2522 3.6840 Image height 10.8150 10.8150 10.8150 Overalllength 144.57 144.57 144.57 of lens system BF 15.97 15.97 15.97 d51.8950 21.0124 39.8115 d12 38.9163 12.8343 1.0000 d17 1.5000 8.46461.5000 d21 3.1000 16.7748 18.8282 d28 27.8290 14.1542 12.1008 Zoom lensunit data Lens Initial Focal unit surface No. length 1 1 68.57962 2 6−12.33387 3 13 33.61459 4 18 36.49963 5 22 −28.99628 6 29 47.34650

TABLE 14 (Various data in a close-object in-focus condition) Zoomingratio 6.41282 Wide-angle Middle Telephoto limit position limit Objectdistance 854.0000 854.0000 854.0000 Focal length 17.5336 50.2145112.4397 F-number 3.61553 4.94320 6.06912 View angle 34.9399 11.89814.5970 Image height 10.8150 10.8150 10.8150 Overall length 144.57 144.57144.57 of lens system BF 15.97 15.97 15.97 d5 1.8951 19.9184 36.8115 d1238.9164 13.9284 4.0000 d17 1.5000 8.4647 1.5000 d21 3.1949 16.728727.3460 d28 27.7342 14.2004 3.5831 Zoom lens unit data Lens InitialFocal unit surface No. length 1 1 68.57962 2 6 −12.33387 3 13 33.61459 418 36.49963 5 22 −28.99628 6 29 47.34650

TABLE 15 (Wobbling values) Second Fifth lens unit lens unit W 0.037−0.006 Sb 0.908 −3.669 e −456.920 −456.920 β_(WO) −0.259 3.415 f_(WO)−12.334 −28.996 β_(R) −0.986 0.587 f_(R) 63.195 47.347

Numerical Example 4

The zoom lens system of Numerical Example 4 corresponds to Embodiment 4shown in FIG. 13. Table 16 shows the surface data of the zoom lenssystem of Numerical Example 4. Table 17 shows the aspherical data. Table18 shows various data in an infinity in-focus condition. Table 19 showsvarious data in a close-object in-focus condition. Table 20 shows thewobbling values of the focusing lens units.

TABLE 16 (Surface data) Surface number r d nd vd Object surface ∞  180.66730 1.50000 1.84666 23.8  2 51.57030 8.08300 1.49700 81.6  3−254.93460 0.15000  4 46.40960 4.73840 1.61800 63.4  5 147.94490Variable  6* −61.74060 0.16590 1.51340 52.9  7 −67.23540 1.05000 1.8830040.8  8 15.08380 3.79040  9 −28.20550 0.80000 1.72916 54.7 10 52.894900.15000 11 31.91530 2.23780 1.94595 18.0 12 −283.71470 Variable 13*17.02280 4.13050 1.68893 31.1 14* −191.74470 1.62030 15 93.51080 0.800001.85014 30.1 16 11.59390 4.42820 1.49700 81.6 17 −197.24180 Variable 18(Diaphragm) ∞ 3.50000 19* 30.50180 3.32490 1.55332 71.7 20 −22.220600.60000 1.80518 25.5 21 −35.74340 Variable 22 20.94320 0.60000 1.8348142.7 23 11.50220 2.38050 24 −17.48170 0.60000 1.80420 46.5 25 67.940602.07030 1.78472 25.7 26 −61.03680 0.15000 27* 32.85520 2.74360 1.5311056.0 28* −60.74640 Variable 29* 20.26020 4.64810 1.50670 70.5 30*85.35460 (BF) Image surface ∞

TABLE 17 (Aspherical data) Surface No. 6 K = 0.00000E+00, A4 =2.18078E−05, A6 = −3.13170E−08, A8 = −6.88758E−10 A10 = 4.10811E−12, A12= 1.05938E−24, A14 = −2.47656E−28 Surface No. 13 K = 0.00000E+00, A4 =−1.01072E−05, A6 = 6.12657E−09, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 14 K = 0.00000E+00, A4 =1.09110E−05, A6 = 1.19433E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 19 K = 0.00000E+00, A4 =−1.02373E−05, A6 = 2.38152E−08, A8 = −5.10196E−10 A10 = 6.20653E−12, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 27 K = 0.00000E+00, A4 =4.15374E−05, A6 = 2.80506E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 28 K = 0.00000E+00, A4 =1.67525E−05, A6 = 1.54487E−07, A8 = 0.00000E+00 A10 = 0.00000E+00, A12 =0.00000E+00, A14 = 0.00000E+00 Surface No. 29 K = 0.00000E+00, A4 =3.95211E−06, A6 = −4.51318E−09, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00 Surface No. 30 K = 0.00000E+00, A4 =2.86326E−05, A6 = −4.15745E−08, A8 = 0.00000E+00 A10 = 0.00000E+00, A12= 0.00000E+00, A14 = 0.00000E+00

TABLE 18 (Various data in an infinity in-focus condition) Zooming ratio9.41742 Wide-angle Middle Telephoto limit position limit Focal length18.5399 56.9050 174.5984 F-number 3.60533 4.94419 5.76838 View angle33.4659 10.7418 3.4958 Image height 10.8150 10.8150 10.8150 Overalllength 144.57 144.57 144.57 of lens system BF 16.24 16.24 16.24 d51.9870 21.0846 39.9552 d12 38.9682 12.2305 1.0000 d17 1.5000 9.13991.5000 d21 3.1000 17.1421 16.1241 d28 28.5066 14.4644 15.4825 Zoom lensunit data Lens Initial Focal unit surface No. length 1 1 67.74704 2 6−12.57199 3 13 35.11067 4 18 34.66952 5 22 −28.32513 6 29 51.20047

TABLE 19 (Various data in a close-object in-focus condition) Zoomingratio 6.25719 Wide-angle Middle Telephoto limit position limit Objectdistance 854.0000 854.0000 854.0000 Focal length 18.5509 53.9950116.0766 F-number 3.61566 4.96838 6.14730 View angle 33.3816 11.08064.3346 Image height 10.8150 10.8150 10.8150 Overall length 144.57 144.57144.57 of lens system BF 16.24 16.24 16.24 d5 1.9870 20.4390 36.9552 d1238.9682 12.8763 4.0000 d17 1.5000 9.1400 1.5000 d21 3.1991 17.681425.4980 d28 28.4076 13.9252 6.1087 Zoom lens unit data Lens InitialFocal unit surface No. length 1 1 67.74704 2 6 −12.57199 3 13 35.11067 418 34.66952 5 22 −28.32513 6 29 51.20047

TABLE 20 (Wobbling values) Second Fifth lens unit lens unit W 0.034−0.006 Sb 0.983 −3.957 e −248.860 −248.860 β_(WO) −0.265 3.441 f_(WO)−12.489 −27.975 β_(R) −1.028 0.604 f_(R) 59.093 50.557

Numerical Example 5

The zoom lens system of Numerical Example 5 corresponds to Embodiment 5shown in FIG. 17. Table 21 shows the surface data of the zoom lenssystem of Numerical Example 5. Table 22 shows the aspherical data. Table23 shows various data in an infinity in-focus condition. Table 24 showsvarious data in a close-object in-focus condition. Table 25 shows thewobbling values of the focusing lens units.

TABLE 21 (Surface data) Surface number r d nd vd Object surface ∞  165.21560 1.00000 1.80518 25.5  2 41.84900 4.84220 1.49700 81.6  3−451.34910 0.15000  4 57.85360 3.24840 1.48749 70.4  5 −1298.88820Variable  6 481.12200 0.90000 1.80610 33.3  7 15.60560 2.18600 1.9459518.0  8 29.53610 Variable  9 −32.91280 0.70000 1.62041 60.3 10 255.13910Variable 11* 18.98460 4.02200 1.71430 38.9 12* −263.25160 1.50000 13(Diaphragm) ∞ 1.52740 14 107.14480 0.80000 1.90366 31.3 15 13.428103.84880 1.49700 81.6 16 292.33830 6.96070 17* 23.39070 3.84370 1.5067070.5 18 −26.00110 0.80000 1.80518 25.5 19 −34.28350 Variable 20 20.571600.60000 1.83481 42.7 21 13.05790 3.11080 22 −28.40360 0.60000 1.7725049.6 23 26.05890 2.94320 1.76182 26.6 24 −32.80830 0.15000 25 50.247700.76850 1.77250 49.6 26 18.16860 Variable 27 17.31000 3.18310 1.5168064.2 28 28.28370 (BF) Image surface ∞

TABLE 22 (Aspherical data) Surface No. 11 K = 0.00000E+00, A4 =−9.65644E−06, A6 = −8.20710E−09 Surface No. 12 K = 0.00000E+00, A4 =3.90372E−06, A6 = 1.18015E−08 Surface No. 17 K = 0.00000E+00, A4 =−2.08147E−05, A6 = 2.47893E−10

TABLE 23 (Various data in an infinity in-focus condition) Zooming ratio3.55770 Wide-angle Middle Telephoto limit position limit Focal length46.3504 82.4158 164.9008 F-number 4.12011 5.25328 5.76839 View angle13.4481 7.3994 3.7506 Image height 10.8150 10.8150 10.8150 Overalllength 117.57 117.57 117.57 of lens system BF 17.09 17.09 17.09 d51.0000 15.3477 30.7796 d8 5.4738 5.1228 3.3464 d10 28.6522 14.65551.0000 d19 8.2124 9.5058 3.2294 d26 9.4521 8.1587 14.4352 Zoom lens unitdata Lens Initial Focal unit surface No. length 1 1 68.08928 2 6−47.64541 3 9 −46.94498 4 11 25.26489 5 20 −17.71059 6 27 78.56489

TABLE 24 (Various data in a close-object in-focus condition) Zoomingratio 2.34663 Wide-angle Middle Telephoto limit position limit Objectdistance 881.0000 881.0000 881.0000 Focal length 43.5533 70.2366102.2032 F-number 4.12056 5.25788 5.90257 View angle 13.7358 7.58634.0601 Image height 10.8150 10.8150 10.8150 Overall length 117.57 117.57117.57 of lens system BF 17.09 17.09 17.09 d5 1.0000 15.3474 28.1396 d83.4900 3.3539 3.9955 d10 30.6362 16.4249 2.9911 d19 8.2124 10.44679.7035 d26 9.4521 7.2179 7.9611 Zoom lens unit data Lens Initial Focalunit surface No. length 1 1 68.08928 2 6 −47.64541 3 9 −46.94498 4 1125.26489 5 20 −17.71059 6 27 78.56489

TABLE 25 (Wobbling values) Second Third Fifth lens unit lens unit lensunit W −0.072 −0.002 −0.010 Sb −0.427 1.167 −4.980 e −33.760 −33.760−33.760 β_(WO) −3.550 0.175 3.258 f_(WO) −47.645 −46.945 −17.711 β_(R)−0.192 −1.097 0.720 f_(R) 39.392 29.252 78.565

Numerical Example 6

The zoom lens system of Numerical Example 6 corresponds to Embodiment 6shown in FIG. 21. Table 26 shows the surface data of the zoom lenssystem of Numerical Example 6. Table 27 shows the aspherical data. Table28 shows various data in an infinity in-focus condition. Table 29 showsvarious data in a close-object in-focus condition. Table 30 shows thewobbling values of the focusing lens units.

TABLE 26 (Surface data) Surface number r d nd vd Object surface ∞  165.87180 1.00000 1.80518 25.5  2 42.07600 5.00710 1.49700 81.6  3−430.79570 0.15000  4 56.94370 3.36930 1.48749 70.4  5 −1501.25820Variable  6 480.89860 0.90000 1.80610 33.3  7 15.47020 2.19580 1.9459518.0  8 29.19040 Variable  9 −32.69450 0.70000 1.62041 60.3 10 268.83430Variable 11* 18.86130 4.10110 1.71430 38.9 12* −243.25930 1.50000 13(Diaphragm) ∞ 1.51790 14 114.11090 0.80000 1.90366 31.3 15 13.420203.84040 1.49700 81.6 16 207.04920 6.59470 17* 22.87250 3.86940 1.5067070.5 18 −25.57270 0.80000 1.80518 25.5 19 −33.55200 Variable 20 20.875800.60000 1.83481 42.7 21 12.74870 3.64520 22 −35.33730 0.60000 1.7725049.6 23 19.85570 2.99650 1.76182 26.6 24 −45.88440 0.15000 25 50.657500.81490 1.77250 49.6 26 18.87760 Variable 27 17.47880 3.19950 1.5168064.2 28 29.69520 (BF) Image surface ∞

TABLE 27 (Aspherical data) Surface No. 11 K = 0.00000E+00, A4 =−1.03291E−05, A6 = −1.03820E−08 Surface No. 12 K = 0.00000E+00, A4 =3.42299E−06, A6 = 1.28109E−08 Surface No. 17 K = 0.00000E+00, A4 =−2.26941E−05, A6 = 6.90506E−10

TABLE 28 (Various data in an infinity in-focus condition) Zooming ratio3.66234 Wide-angle Middle Telephoto limit position limit Focal length46.3493 88.6883 169.7469 F-number 4.12022 5.25319 5.76810 View angle13.4101 6.8484 3.6392 Image height 10.8150 10.8150 10.8150 Overalllength 117.57 117.57 117.57 of lens system BF 16.96 16.96 16.96 d51.0000 16.8403 31.1023 d8 5.3504 5.2090 3.3881 d10 29.1399 13.44101.0000 d19 8.3176 9.5926 3.1000 d26 8.4469 7.1719 13.6646 Zoom lens unitdata Lens Initial Focal unit surface No. length 1 1 67.86546 2 6−46.99459 3 9 −46.94255 4 11 25.09520 5 20 −16.73602 6 27 75.47658

TABLE 29 (Various data in a close-object in-focus condition) Zoomingratio 2.32997 Wide-angle Middle Telephoto limit position limit Objectdistance 881.0000 881.0000 881.0000 Focal length 43.5025 73.5782101.3595 F-number 4.12068 5.25740 5.91040 View angle 13.6883 7.02843.9954 Image height 10.8150 10.8150 10.8150 Overall length 117.57 117.57117.57 of lens system BF 16.96 16.96 16.96 d5 1.0000 16.8400 28.1023 d83.3849 3.3849 4.1912 d10 31.1055 15.2655 3.1969 d19 8.3176 10.69049.8519 d26 8.4470 6.0742 6.9128 Zoom lens unit data Lens Initial Focalunit surface No. length 1 1 67.86546 2 6 −46.99459 3 9 −46.94255 4 1125.09520 5 20 −16.73602 6 27 75.47658

TABLE 30 (Wobbling values) Second Third Fifth lens unit lens unit lensunit W −0.074 −0.003 −0.011 Sb −0.427 1.179 −5.164 e −31.936 −31.936−31.936 β_(WO) −3.418 0.181 3.341 f_(WO) −46.994 −46.943 −16.736 β_(R)−0.200 −1.104 0.713 f_(R) 38.998 28.520 75.477

The following Table 31 shows the corresponding values to the individualconditions in the zoom lens systems of each of Numerical Examples.

TABLE 31 (Values corresponding to conditions) Example Condition 1 2 3 45 6 (1) T₁/f_(w) 0.5459 0.4941 0.8411 0.7806 0.1994 0.2055 (2) (T₁ +T₂)/f_(w) 1.0091 0.9168 1.3367 1.2225 0.2659 0.2723 T₁ 9.5595 9.159714.7284 14.4714 9.2406 9.5264 T₂ 8.1099 7.8378 8.6779 8.1941 3.08603.0958 f_(w) 17.5100 18.5399 17.5100 18.5399 46.3504 46.3493

The zoom lens system according to the present invention is applicable toa digital still camera, a digital video camera, a camera for a mobiletelephone, a camera for a PDA (Personal Digital Assistance), asurveillance camera in a surveillance system, a Web camera, avehicle-mounted camera or the like. In particular, the zoom lens systemaccording to the present invention is suitable for a photographingoptical system where high image quality is required like in a digitalstill camera system or a digital video camera system.

Also, the zoom lens system according to the present invention isapplicable to, among the interchangeable lens apparatuses according tothe present invention, an interchangeable lens apparatus havingmotorized zoom function, i.e., activating function for the zoom lenssystem by a motor, with which a digital video camera system is provided.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodification depart from the scope of the present invention, they shouldbe construed as being included therein.

1. A zoom lens system comprising a plurality of lens units, each lensunit comprising at least one lens element, wherein the plurality of lensunits include a plurality of movable lens units which individually movealong an optical axis at the time of zooming from a wide-angle limit toa telephoto limit during image taking, at least two of the movable lensunits are focusing lens units which move along the optical axis at thetime of focusing from an infinity in-focus condition to a close-objectin-focus condition in at least one zooming position from a wide-anglelimit to a telephoto limit, and among the focusing lens units, a lensunit having the absolute value, which is not the greatest absolutevalue, of a wobbling value at a wide-angle limit represented by thefollowing expression (a) is a wobbling lens unit which senses a movingdirection of the focusing lens units at the time of focusing by wobblingitself in a direction along the optical axis:W=1/e+β _(WO)/(Sb×f _(WO))−1/((β_(R) ×f _(R))  (a) where W is a wobblingvalue at a wide-angle limit (wobbling incremental magnificationsensitivity), Sb is a focus sensitivity of the wobbling lens unitrepresented by the following expressionSb=(1−β_(WO) ²)×β_(R) ², e is an exit pupil position of the entiresystem at a wide-angle limit, β_(WO) is a paraxial lateral magnificationof the wobbling lens unit at a wide-angle limit in an infinity in-focuscondition, f_(WO) is a focal length of the wobbling lens unit at awide-angle limit in an infinity in-focus condition, β_(R) is a paraxiallateral magnification of a system on the image side relative to thewobbling lens unit at a wide-angle limit in an infinity in-focuscondition, and f_(R) is a focal length of a system on the image siderelative to the wobbling lens unit at a wide-angle limit in an infinityin-focus condition.
 2. The zoom lens system as claimed in claim 1,wherein a lens unit located closest to the object side is fixed relativeto an image surface at the time of zooming from a wide-angle limit to atelephoto limit during image taking.
 3. The zoom lens system as claimedin claim 1, wherein a lens unit having an aperture diaphragm is fixedrelative to the image surface at the time of zooming from a wide-anglelimit to a telephoto limit during image taking.
 4. The zoom lens systemas claimed in claim 1, wherein a lens unit located closest to the imageside is fixed relative to the image surface at the time of zooming froma wide-angle limit to a telephoto limit during image taking.
 5. The zoomlens system as claimed in claim 1, wherein the lens unit located closestto the object side has positive optical power.
 6. The zoom lens systemas claimed in claim 1, wherein at the time of focusing from an infinityin-focus condition to a close-object in-focus condition in the samezooming position from a wide-angle limit to a telephoto limit duringimage taking, the ratio of an amount of movement of a focusing lens unitα, which is one of the focusing lens units, to an amount of movement ofa focusing lens unit β, which is one of the focusing lens units and isdifferent from the focusing lens unit α, is constant regardless of theobject distance.
 7. The zoom lens system as claimed in claim 1, whereinan aperture diaphragm is either included in a lens unit which is locatedhaving two air spaces toward the image side from the lens unit locatedclosest to the object side, or located on the image side relative to thelens unit which is located having two air spaces toward the image sidefrom the lens unit located closest to the object side.
 8. The zoom lenssystem as claimed in claim 1, wherein the plurality of lens unitsinclude an image blur compensating lens unit which moves in a directionperpendicular to the optical axis in order to optically compensate imageblur.
 9. The zoom lens system as claimed in claim 1, wherein thefollowing condition (1) is satisfied:0.1<T ₁ /f _(W)<1.5  (1) where T₁ is an axial thickness of the lens unitlocated closest to the object side, and f_(W) is a focal length of theentire system at a wide-angle limit.
 10. The zoom lens system as claimedin claim 1, wherein the following condition (2) is satisfied:0.1<(T ₁ +T ₂)/f _(W)<2.5  (2) where T₁ is an axial thickness of thelens unit located closest to the object side, T₂ is an axial thicknessof a lens unit which is located having one air space toward the imageside from the lens unit located closest to the object side, and f_(W) isa focal length of the entire system at a wide-angle limit.
 11. Aninterchangeable lens apparatus comprising: the zoom lens system asclaimed in claim 1; and a lens mount section which is connectable to acamera body including an image sensor for receiving an optical imageformed by the zoom lens system and converting the optical image into anelectric image signal.
 12. A camera system comprising: aninterchangeable lens apparatus including the zoom lens system as claimedin claim 1; and a camera body which is detachably connected to theinterchangeable lens apparatus via a camera mount section, and includesan image sensor for receiving an optical image formed by the zoom lenssystem and converting the optical image into an electric image signal.